Modern automatic air conditioning (AC) systems provide cooling for comfort while driving. Generally described, the AC cycle includes four basic stages: 1) a saturated vapor of a refrigerant, generally 1,1,1,2-tetrafluoroethane (R134A) [or chlorofluorocarbons sold under the trademark FREON®], is compressed by an in-line compressor to high pressure and forms a superheated vapor; 2) the compressed vapor is stripped of excess heat and condenses in a heat exchanger (termed a condenser coil), generally by transferring rejected heat to an ambient airstream drawn or blown across the coil; 3) the saturated liquid is then passed through an expansion device, termed here a “Venturi” (an in-line flow constrictor typically known as an “expansion valve” or a “throttle tube”), that results in a pressure drop and a phase change of at least some of the liquid to a gas by a process known as “adiabatic flash evaporation”. The chilled vapor is then pumped to a second heat exchanger and blower combination and used to cool the vehicle's interior; 4) finally, the exhausted vapor is returned to the compressor and the cycle renews. Variations of this basic AC cycle are known and also may require the tool described here.
Thus servicing these systems requires close contact with hot surfaces, fan blades, and belts used to drive the compressor and the blowers. Moreover, servicing generally must be performed when the AC system is operating at steady state so that the pressure drop in the Venturi can be set to factory specifications. Before that, it may be necessary to open the system (without releasing refrigerant into the atmosphere) and to supply fresh refrigerant, a tightly regulated process because of the danger the released gases pose to the Earth's ozone shield.
When the correct pressure drop is not obtained, or system performance weakens, it may be necessary to add gas. Typical systems contain 2.5 to 3.5 pounds of refrigerant, which is expensive and heavily regulated. For this reason, gas-tight quick-release nipples (or “taps”) have been developed that allow a licensed mechanic to access the system upstream and downstream of the Venturi, to add or remove gas through a valved “tee”, and to enable pressure gauges during adjustments on the system. These taps are generally placed around the engine block and evaporator and often end up in cramped and difficult to access cavities, such as between the radiator and the evaporator. Mechanics may develop open sores and burns because of repeated damage to the knuckles and wrists that occurs during installation of system test valves on the quick-connect fittings and when making the required adjustments. Unfortunately, the high and low taps that must be accessed for testing and maintenance frequently are placed in poorly accessible cavities within the engine department.
Thus, servicing automotive air-conditioning systems can be a hot and dangerous job. Adjustments are generally made at full temperature and pressure while the AC system is in operation, and finger and hand damage frequently results from the required close contact with hot surfaces and moving parts such as belts and fan blades. Steady state conditions for proper adjustment of an AC system require that the temperature be 93 degrees Celsius or higher (200° F.).
Correct adjustment of the fluid pressure in the AC system is necessary to ensure proper operation and helps to minimize the overall consumption and waste of these environmentally dangerous refrigerant gases.
Clearly, there is a need in the art for a tool that overcomes the above dangers and disadvantages when working with inaccessible quick-connect valves and nozzles during AC system service. The tool must be capable of multiple functions that a mechanic would otherwise perform by hand. The tool must assist the mechanic in positioning a valve T-adapter over a tap in blind positions, the quick-connect locking sleeve of the adaptor must then be depressed so as to engage the tap nipple and released when in place to form a gas-tight seal, and the valve on/off knob must then be opened. Typically the “tee” is connected through a manifold to a reservoir for receiving waste gas or a fresh gas reservoir attached to recharge the system. These steps are required to improve performance of depleted systems and to retrofit the older FREON®-based systems with the newer R134A. Generally a pair of pressure gauges are used: one at the high pressure tap, and the other at the low pressure tap. After the ΔP across the Venturi is adjusted per the manufacturer's specifications, the test fittings and gauges must be removed. To remove the valve T-adapters, the valve is first securely closed and the valve assembly is then physically compressed to force the quick-release sleeve into its unlocked (depressed) position. While maintaining compression, the sleeve can be released from its engagement on mated lips formed on the nipple of the tap. Preferably, these operations would be performed with a single tool in a stepwise sequence so that the valve assembly remains captive in the tool head for easy recovery. No ordinary tool of the art suffices to perform all of these operations without dangerous release of gas and without potential injury to hands and fingers.
It is also known that the geometry and accessibility of AC systems varies according to the vehicle make and model. Tap adaptor fittings may also vary in dimensions. Thus it is desirable that a tool be conceived which permits these operations without requiring the mechanic to have a completely different tool for each vehicle type.
A solution to these interrelated problems is only achieved by trial and error. There has been a long-standing need for a tool that overcomes these difficulties. Only a tool that can install and remove a quick-connect valve and can, without releasing the valve, rotatingly open and close the valve is sufficient to solve the problem. Many burned knuckles have led me to the solution disclosed here.